U.S. patent application number 10/377877 was filed with the patent office on 2003-12-25 for air conditioning system with two compressors and method for operating the same.
This patent application is currently assigned to LG Electronics Inc.. Invention is credited to Choi, Chang Min, Huh, Deok, Hwang, Yoon Jei, Kim, Cheol Min, Lee, Won Hee.
Application Number | 20030233838 10/377877 |
Document ID | / |
Family ID | 29728711 |
Filed Date | 2003-12-25 |
United States Patent
Application |
20030233838 |
Kind Code |
A1 |
Lee, Won Hee ; et
al. |
December 25, 2003 |
Air conditioning system with two compressors and method for
operating the same
Abstract
Disclosed are an air conditioning system with two compressors so
as to shorten standby time for re-operating a stopped compressor
and variably change the compression capacity of a refrigerant
according to cooling load, and a method for operating the air
conditioning system. The method for operating the air conditioning
system with two compressors, comprises the first step of
simultaneously operating the compressors regardless of cooling load
at an early stage of the operation, the second step of selectively
operating one of the compressors according to the cooling load, and
the third step of additionally re-operating the stopped compressor
when the operated compressor selected from the compressor in the
second step is continuously operated for longer than a designated
time, thereby shortening the standby time for re-operating the
stopped compressor, rapidly changing the compression capacity of
the refrigerant according to the cooling load, and improving users'
comfort within a room.
Inventors: |
Lee, Won Hee; (Seoul-si,
KR) ; Choi, Chang Min; (Seoul-si, KR) ; Hwang,
Yoon Jei; (Seoul, KR) ; Huh, Deok; (Buchun-si,
KR) ; Kim, Cheol Min; (Kwangmyung-si, KR) |
Correspondence
Address: |
GREENBLUM & BERNSTEIN, P.L.C.
1950 ROLAND CLARKE PLACE
RESTON
VA
20191
US
|
Assignee: |
LG Electronics Inc.
Seoul
KR
|
Family ID: |
29728711 |
Appl. No.: |
10/377877 |
Filed: |
March 4, 2003 |
Current U.S.
Class: |
62/175 ;
62/510 |
Current CPC
Class: |
F25B 2700/2104 20130101;
F25B 2600/0251 20130101; F25B 13/00 20130101; F25B 2600/02
20130101; F25B 49/022 20130101; F25B 2400/0751 20130101 |
Class at
Publication: |
62/175 ;
62/510 |
International
Class: |
F25B 007/00; F25B
001/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 19, 2002 |
KR |
2002-34364 |
Claims
What is claimed is:
1. An air conditioning system with two compressors, comprising: an
air conditioner for conditioning air of a room so as to satisfy
cooling load via a cooling cycle formed by a refrigerant passing
through compressors, a condenser, an expansion valve, and an
evaporator; and a control unit for selectively or simultaneously
operating the compressors according to a variation of the cooling
load so as to variably control a compression capacity of the
refrigerant.
2. The air conditioning system with two compressors as set forth in
claim 1, wherein the air conditioner includes: two compressors for
compressing a gaseous refrigerant in a low-temperature and
low-pressure state so as to convert it into a high-temperature and
high-pressure state; a condenser for condensing the gaseous
refrigerant in the high-temperature and high-pressure state so as
to convert it into a liquid refrigerant in a mid-temperature and
high-pressure state; an expansion valve for decompressing the
liquid refrigerant in the mid-temperature and high-pressure state
so as to convert it into a low-temperature and low-pressure state;
and an evaporator for evaporating the liquid refrigerant in the
low-temperature and low-pressure state so as to convert it into a
gaseous refrigerant in a low-temperature and low-pressure
state.
3. The air conditioning system with two compressors as set forth in
claim 1, wherein the control unit includes: a comparing unit for
judging whether the cooling load is heavy or light; a measuring
unit for measuring an operating time of an operated compressor
selected from the two compressors; and a compressor-driving unit
for outputting a control signal for selectively or simultaneously
operating the compressors according to the variation of the cooling
load and the operating time.
4. The air conditioning system with two compressors as set forth in
claim 3, wherein the comparing unit judges whether a difference
between a desired room temperature and a real room temperature
exceeds a reference value, and thereby determining whether the
cooling load is heavy or light.
5. The air conditioning system with two compressors as set forth in
claim 3, wherein the compressor-driving unit outputs a control
signal for simultaneously operating all of the compressors when the
cooling load is increased or when the operating time of the
operated compressor exceeds a designated time.
6. A method for operating an air conditioning system with two
compressors, comprising: the first step of simultaneously operating
the compressors regardless of cooling load at an early stage of the
operation; the second step of selectively operating one of the
compressors according to the cooling load; and the third step of
additionally re-operating the stopped compressor when the operated
compressor selected from the compressor in the second step is
continuously operated for longer than a designated time.
7. The method for operating an air conditioning system with two
compressors as set forth in claim 6, wherein the second step
includes: the first sub-step of obtaining a difference between a
desired room temperature and a real room temperature; the second
sub-step of comparing the temperature difference obtained by the
first sub-step to a reference value; and the third sub-step of
judging that the cooling load is heavy when the temperature
difference exceeds the reference value, or judging that the cooling
load is light when the temperature difference does not exceed the
reference value.
8. The method for operating an air conditioning system with two
compressors as set forth in claim 6, wherein the third step
includes: the first sub-step of measuring an operating time of the
operated compressor selected from the compressors; the second
sub-step of comparing the operating time to the designated time;
and the third sub-step of additionally re-operating the stopped
compressor when the operating time exceeds the designated time.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an air conditioning system
with two compressors and a method for operating the same, and more
particularly to an air conditioning system with two compressors, so
as to shorten standby time for re-operating a stopped compressor,
and a method for operating the air conditioning system.
[0003] 2. Description of the Related Art
[0004] Generally, an air conditioner comprises a compressor for
compressing a gaseous refrigerant in a low-temperature and
low-pressure state so as to convert it into a high-temperature and
high-pressure state, a condenser for condensing the gaseous
refrigerant in the high-temperature and high-pressure state
compressed by the compressor so as to convert it into a liquid
refrigerant in a high-temperature and high-pressure state, and an
evaporator for evaporating the liquid refrigerant in the
high-temperature and high-pressure state condensed by the condenser
so as to convert it into a gaseous refrigerant in a low-temperature
and low-pressure state. A heat pump air conditioner, additionally
having a heating function, further comprises a four-way valve for
converting a flow direction of the refrigerant according to cooling
and heating modes.
[0005] In such a heat pump air conditioner, an indoor heat
exchanger and an outdoor heat exchanger have different functions
according to their cooling and heating modes. That is, the indoor
heat exchanger serves as the condenser and the outdoor heat
exchanger serves as the evaporator in the heating mode, thereby
forming a heating cycle. On the other hand, the indoor heat
exchanger serves as the evaporator and the outdoor heat exchanger
serves as the condenser in the cooling mode, thereby forming a
cooling cycle. Therefore, the heat pump air conditioner is
unlimitedly applicable in all seasons.
[0006] Hereinafter, the air conditioner for forming the cooling
cycle and the heat pump air conditioner for forming the cooling and
heating cycles are generally referred to as an air conditioner.
[0007] Recent, air conditioners employ a plurality of compressors
having different capacities, thereby variably changing a
compression capacity of the refrigerant and optimizing cooling and
heating efficiencies.
[0008] FIG. 1 is a block diagram illustrating a flow of a
refrigerant of a conventional air conditioner in a cooling mode,
and FIG. 2 is a graph illustrating operating states of compressors
in the conventional air conditioner. With reference to FIGS. 1 and
2, a method for operating the conventional air conditioner is
described, as follows.
[0009] FIG. 1 is a block diagram illustrating the flow of the
refrigerant of the conventional air conditioner in the cooling
mode. The conventional air conditioner comprises a plurality of
compressors 10 for compressing a gaseous refrigerant in a
low-temperature and low-pressure state so as to convert it into a
high-temperature and high-pressure state. The compressors 10
includes first and second compressors 11 and 12, having different
compression capacities of the refrigerant.
[0010] Each of the first and second compressors 11 and 12 has a
designated compression capacity of the refrigerant, so as to
compress a specific percentage of the total capacity (100%) of the
refrigerant. The compression capacities of the refrigerant of the
first and second compressors 11 and 12 are set by a manufacturer.
Herein, the first compressor 11 has a 60% compression capacity of
the refrigerant, and the second compressor 12 has a 40% compression
capacity of the refrigerant.
[0011] Therefore, the total compression capacity of the refrigerant
in the air conditioner is variably changed by selectively or
simultaneously operating the first compressor 11 and the second
compressor 12 according to a cooling load.
[0012] The conventional air conditioner further comprises check
valves 13 and 14, a four-way valve 20, an outdoor heat exchanger
30, an expansion valve 40, an indoor heat exchanger 50, and an
accumulator 60, thereby forming a cooling cycle via a flow of the
refrigerant. The check valves 13 and 14 respectively prevent the
reverse-flow of the refrigerant compressed by the first and second
compressors 11 and 12. The four-way valve 20 converts the flow
direction of the refrigerant passing through the first and second
compressors 11 and 12, thereby reversing functions of the outdoor
and indoor heat exchangers 30 and 50. The outdoor heat exchanger 30
exchanges heat between external air and the refrigerant, thereby
condensing the gaseous refrigerant in the high-temperature and
high-pressure state, so as to convert it into a liquid refrigerant
in a mid-temperature and high-pressure state. The expansion valve
40 decompresses the liquid refrigerant passing through the outdoor
heat exchanger 30, so as to convert it into a low-temperature and
low-pressure state. The indoor heat exchanger 50 exchanges heat
between the indoor air and the refrigerant passing through the
expansion valve 40 so as to convert it into a two-phase refrigerant
in liquid and gaseous phases. The accumulator 60 separates the
liquid phase from the two-phase refrigerant passing through the
indoor heat exchanger 50, and then supplies only the gaseous phase
to the first and second compressors 11 and 12.
[0013] When the cooling or heating load is relatively light, only
the second compressor 12 of the air conditioner is operated.
Herein, the first compressor 11 is stopped, and the check valve 13
of the first compressor 11 is closed.
[0014] Therefore, the gaseous refrigerant compressed in the
high-pressure state, which is discharged from an outlet 11b of the
first compressor 11 and then supplied to the check valve 13, is cut
off, and then high pressure at the outlet 11b of the first
compressor 11 is maintained. Since the gaseous refrigerant at an
inlet 11a of the first compressor 11 is not yet compressed, low
pressure at an inlet 11a of the first compressor 11 is maintained.
Therefore, a pressure difference between the inlet 11a and the
outlet 11b of the compressor 11 is generated.
[0015] When the pressures at the inlet 11a and the outlet 11b of
the compressor 11 are equalized so as to remove the pressure
difference, the stopped compressor 11 is re-operated. Standby time
for re-operating the stopped compressor 11 is the same as the time
taken to equalize the pressures at the inlet 11a and the outlet 11b
of the compressor 11.
[0016] When the high-pressure refrigerant around the outlet 11b
moves toward the inlet 11a during the pressure equilibrium time, so
as to equalize the pressures at the inlet 11a and the outlet 11b of
the compressor 11, oil used to operate the first compressor 11
leaks via gaps formed through the first compressor 11 and is
accumulated in a pipe (P1) connected to the inlet 11a. When the
first compressor 11 is re-operated and the refrigerant flows into
the first compressor 11 via the inlet 11a, the leaking oil
accumulated in the pipe (P1) flows into the first compressor 11,
together with the refrigerant.
[0017] However, when the first compressor 11 is stopped for a long
time, the leaking oil accumulated in the pipe (P1) is solidified
and an inner surface of the pipe (P1) becomes uneven. The uneven
inner surface of the pipe (P1) with the solidified oil obstructs
the flow of the refrigerant to re-operate the first compressor 11,
thereby extending the standby time for re-operating the stopped
compressor 11. Further, when the standby time is extended, the air
conditioner cannot rapidly cope with the variation of the cooling
load, thereby not satisfying users' comfort requirement within a
room.
[0018] With reference to FIG. 2, the operating states of the
compressors of the conventional air conditioner is described as
follows.
[0019] When a cooling order is inputted to the air conditioner and
the compressors are operated, the second compressor having the 40%
compression capacity of the refrigerant is first operated, and
later the first compressor having the 60% compression capacity of
the refrigerant is additionally operated. Then, the total
compression capacity of the refrigerant becomes 100% (F1) and a
cooling cycle starts so that the room temperature reaches a desired
temperature.
[0020] When the room temperature reaches the desired temperature,
the compressors are stopped. Then, when the room temperature rises,
the compressors are simultaneously operated again so as to lower
the room temperature, and later only one compressor is continuously
operated so as to maintain the lowered room temperature. Herein,
the second compressor is continuously operated and the first
compressor is stopped for a long time (PT).
[0021] In order to satisfy an increased cooling load, the stopped
first compressor must be additionally re-operated together with the
second compressor. At this time, standby time for re-operating the
stopped first compressor is extended due to the above-described
problem, and then the increased cooling load is not rapidly
satisfied.
SUMMARY OF THE INVENTION
[0022] Therefore, the present invention has been made in view of
the above problems, and it is an object of the present invention to
provide an air conditioning system with two compressors and a
method for operating the same, in which standby time for
re-operating a stopped compressor is shortened by forcibly
operating the stopped compressor regardless of cooling load when
the stopped compressor maintains its stopped state for longer than
a designated time, thereby rapidly satisfying the variation of the
cooling load and improving users' comfort in a room.
[0023] In accordance with one aspect of the present invention, the
above and other objects can be accomplished by the provision of an
air conditioning system with two compressors, comprising:
[0024] an air conditioner for conditioning air of a room so as to
satisfy cooling load via a cooling cycle formed by a refrigerant
passing through compressors, a condenser, an expansion valve, and
an evaporator; and
[0025] a control unit for selectively or simultaneously operating
the compressors according to a variation of the cooling load so as
to variably control a compression capacity of the refrigerant.
[0026] In accordance with another aspect of the present invention,
there is provided a method for operating an air conditioning system
with two compressors, comprising:
[0027] the first step of simultaneously operating the compressors
regardless of cooling load at an early stage of the operation;
[0028] the second step of selectively operating one of the
compressors according to the cooling load; and
[0029] the third step of additionally re-operating the stopped
compressor when the operated compressor selected from the
compressor in the second step is continuously operated for longer
than a designated time.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The above and other objects, features and other advantages
of the present invention will be more clearly understood from the
following detailed description taken in conjunction with the
accompanying drawings, in which:
[0031] FIG. 1 is a block diagram illustrating a flow of a
refrigerant in a conventional air conditioner;
[0032] FIG. 2 is a graph illustrating operating states of
compressors in the conventional air conditioner;
[0033] FIG. 3 is a block diagram of an air conditioning system with
two compressors in accordance with the present invention;
[0034] FIG. 4 is a graph illustrating operating states of
compressors in the air conditioning system with two compressors in
accordance with the present invention;
[0035] FIG. 5 is a flow chart illustrating a method for operating
the air conditioning system with two compressors in accordance with
the present invention; and
[0036] FIG. 6 is a graph illustrating standby times for operating
the conventional compressors and the compressors of the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0037] Now, preferred embodiments of the present invention will be
described in detail with reference to the annexed drawings.
[0038] FIG. 3 is a block diagram of an air conditioning system with
two compressors in accordance with the present invention, and FIG.
4 is a graph illustrating operating states of compressors in the
air conditioning system with two compressors in accordance with the
present invention.
[0039] An air conditioner of the present invention is similar to
the conventional air conditioner of FIG. 1. In FIG. 3, a solid
arrow denotes a flow of a control signal from a control unit to
each component of the air conditioner, and a dotted arrow denotes a
flow of a refrigerant between components of the air conditioner.
With reference to FIG. 3, the air conditioning system of the
present invention is described as follows.
[0040] Compressors 100 suck a gaseous refrigerant evaporated by an
evaporator, and then compress the sucked gaseous refrigerant so as
to convert it into a high-pressure state. Thereby, kinetic energy
of the molecules within the gaseous refrigerant is increased,
thereby causing collisions between the molecules. Then, energy
generated by the collisions between the molecules raises the
temperature of the gaseous refrigerant so that the gaseous
refrigerant is converted into a high-temperature and high-pressure
state. Since the above gaseous refrigerant has an increased number
of molecules per unit volume, the gaseous refrigerant is easily
liquefied at room temperature.
[0041] The compressors 100 of the air conditioning system of the
present invention include a first compressor 110 and a second
compressor 120. Each of the first and second compressors 110 and
120 has a designated compression capacity of the refrigerant so as
to compress a specific percentage of the total capacity (100%) of
the refrigerant. Herein, the compression capacities of the
refrigerant of the first and second compressors 110 and 120 are set
by a manufacturer. In accordance with a preferred embodiment of the
present invention, the first compressor 110 has a 60% compression
capacity of the refrigerant, and the second compressor 120 has a
40% compression capacity of the refrigerant. However, the
compression capacity of each compressor is not limited thereto.
[0042] A condenser 300 removes heat from the gaseous refrigerant in
the high-temperature and high-pressure state discharged from the
compressors 100, thereby liquefying the gaseous refrigerant so as
to convert it into a liquid refrigerant in a mid-temperature and
high-pressure state.
[0043] An expansion valve 400 expands the liquid refrigerant in the
mid-temperature and high-pressure state, thereby reducing the
pressure of the liquid refrigerant so as to convert it into a
low-temperature and low-pressure state.
[0044] An evaporator 500 absorbs heat from indoor air, thereby
evaporating the liquid refrigerant in the low-temperature and
low-pressure state so as to convert it into a gaseous refrigerant
in a low-temperature and low-pressure state, thus cooling a
room.
[0045] A heat pump air conditioner, additionally having a heating
function, further comprises a four-way valve 200 represented in a
dotted line of FIG. 3. Herein, a control unit 600 controls the
four-way valve 200 to convert a circulation direction of the
refrigerant according to cooling and heating modes.
[0046] The control unit 600 controls the operations of all
components, i.e., the compressors 100, the condenser 300, the
expansion valve 400, and the evaporator 500 so as to initiate a
cooling function. In case of the heat pump air conditioner
additionally having heating function, the control unit 600 controls
the four-way valve 200 to convert a flow direction of the
refrigerant.
[0047] The control unit 600 of the air conditioning system
comprising the two compressors 110 and 120 of the present invention
includes a comparing unit 610, a measuring unit 620, and a
compressor-driving unit 630. The comparing unit 610 judges whether
the cooling load is heavy or light. The measuring unit 620 measures
an operating time of an operated compressor selected from the
compressors. The compressor-driving unit 630 outputs a control
signal for selectively or simultaneously operating the compressors
according to the variation of the cooling load and the operating
time.
[0048] The comparing unit 610 compares a difference between a
desired room temperature and a real room temperature to a reference
value, thereby judging whether the cooling load is heavy or light.
The measuring unit 620 measures the operating time of the operated
compressor selected from the compressors. In case the operating
time exceeds a designated time, the non-operated compressor
maintains its stopped state for longer than the designated time.
Therefore, the measuring unit 620 serves to prevent the extension
of standby time for re-operating the stopped compressor when all of
the compressors are simultaneously operated according to the heavy
cooling load.
[0049] Therefore, when the measuring unit 610 judges that the
cooling load is heavy, or that the operating time of the operated
compressor has exceeded the designated time, the compressor-driving
unit 630 outputs a control signal for simultaneously operating the
first compressor 110 and the second compressor 120.
[0050] FIG. 4 is a graph illustrating operating states of
compressors in the air conditioning system with two compressors in
accordance with the present invention, and FIG. 5 is a flow chart
illustrating a method for operating the air conditioning system
with two compressors in accordance with the present invention. With
reference to FIGS. 4 and 5, the method for operating the air
conditioning system with two compressors is described in detail as
follows.
[0051] When a user inputs a desired room temperature into the air
conditioning system so as to cool or heat a room (S1), in order to
satisfy cooling load according to the desired room temperature, all
of the compressors are simultaneously operated (F1') so that the
compression capacity of the refrigerant becomes 100%, and the air
conditioning system of the present invention discharges cool air
via the cooling cycle. Herein, a case of simultaneously operating
all of the compressors of the air conditioning system is referred
to as a full operation.
[0052] The full operation is repeated at designated times so as to
rapidly satisfy the cooling load. (S2) In the preferred embodiment
of the present invention, the number of times of full operation is
predetermined to be twice.
[0053] When the room temperature reaches the desired room
temperature, the compressors are stopped. Then, the variation of
the room temperature is determined. That is, the comparing unit of
the control unit obtains a difference between the desired room
temperature and the real room temperature (S3), and determines
whether the temperature difference exceeds the reference value
(S4). When the temperature difference exceeds the reference value,
the measuring unit judges that the cooling load is heavy, and when
the temperature difference does not exceeds the reference value,
the measuring unit judge that the cooling load is light.
[0054] The compressor-driving unit of the control unit selectively
or simultaneously operates the compressors according to the
variation of the cooling load. When the cooling load is heavy, the
compressor-driving unit outputs a control signal for simultaneously
operating all of the compressors (S8). When the cooling load is
light, the compressor-driving unit selectively operates one part of
the compressors (S5). That is, in the preferred embodiment of the
present invention, only the second compressor is operated and the
first compressor is stopped.
[0055] The measuring unit of the control unit measures the
operating time of the compressor selected from the compressors
(S6). When the operating time of the operated compressor exceeds
the designated time (PT') (S7), the stopped first compressor is
additionally re-operated so that all of the compressors are
simultaneously operated (F2') (S8). On the other hand, when the
operating time does not exceeds the designated time, only the
selected compressor is continuously operated (S5).
[0056] Therefore, the control unit determines whether the operating
time of the operated compressor selected from the compressors
exceeds the designated time, and additionally re-operates the
stopped compressor according to the determined result so that all
of the compressors are simultaneously operated, thereby preventing
leaking oil from being accumulated in the pipes of the stopped
compressor, and shortening time taken to equalize pressures at an
inlet and an outlet of the stopped compressor in the re-operation
of the stopped compressor. That is, the conventional pressure
equilibrium time (T) is shortened into the pressure equilibrium
time (T') of the present invention. A Graph of FIG. 6 comparatively
illustrates standby time for re-operating the conventional stopped
compressor and standby time for re-operating the stopped compressor
of the present invention.
[0057] The thin upper curve of FIG. 1 illustrates the conventional
pressure equilibrium time (T), and the bold lower curve of FIG. 1
illustrates the pressure equilibrium time (T') of the present
invention. The standby time for re-operating the stopped compressor
of the present invention is shortened due to the shortened pressure
equilibrium time (T').
[0058] As apparent from the above description, the present
invention provides an air conditioning system with two compressors
and a method for manufacturing the air conditioning system, in
which the compressors are simultaneously operated so that time for
maintaining the stopped state of a stopped compressor does not
exceed a designated time, thereby shortening time taken to equalize
pressures at an inlet and an outlet of the stopped compressor and
then shortening standby time for simultaneously operating the
compressors so as to satisfy the increase of a cooling load. Thus,
the air conditioning system with two compressors of the present
invention rapidly copes with the variation of the cooling load,
thereby variably changing a compression capacity of the refrigerant
and satisfying the cooling load.
[0059] Although the preferred embodiments of the present invention
have been disclosed for illustrative purposes, those skilled in the
art will appreciate that various modifications, additions and
substitutions are possible, without departing from the scope and
spirit of the invention as disclosed in the accompanying claims.
For example, the compression capacity of each compressor is not
limited to the above-described value, but may be variably set by a
manufacturer. Further, the above-described technique for shortening
standby time for re-operating the stopped compressor when the
stopped compressor maintains its stopped state for longer than the
designated time may be applied to other fields.
* * * * *